Many heavy metals have been shown to affect neurotransmitter function. Levels of neurotransmitters and their turnover rates have been found to be altered. No data exists on the effect of metals on postsynaptic binding events. This work involves measurement of effects of organic and inorganic derivatives of lead and mercury upon neurotransmitter receptors. This locus is a critical and often rate-limiting area of nerve function. In vivo and in vitro effects of these metals will be assayed. The developmental aspects of metal effects upon receptor characteristics is of special interest in view of the vulnerability of the immature nervous system to these neurotoxic compounds.